3 frenched racks of lamb (8 ribs and 1 1/2 lb each rack), trimmed of all but a thin layer of fat, then brought to room temperature

2 tablespoons Dijon mustard

Special equipment: an instant-read thermometer

Preparation

Stir together bread crumbs, parsley, mint, rosemary, salt, and pepper in a bowl, then drizzle with 2 1/2 tablespoons oil and toss until combined well.

Put oven rack in middle position and preheat to 400°F.

Season lamb with salt and pepper. Heat remaining tablespoon oil in a large heavy skillet over moderately high heat until hot but not smoking, then brown lamb 1 rack at a time, turning once, about 4 minutes per rack. Transfer to a 13- by 9- by 2-inch roasting pan, arranging fatty sides up.

Spread fatty sides of each rack with 2 teaspoons mustard. Divide bread crumb mixture into 3 portions and pat each portion over mustard coating on each rack, gently pressing to adhere.